Spring brake cylinder with an emergency release device

ABSTRACT

The invention relates to a spring brake cylinder with an emergency release device, comprising the following: a housing ( 4 ) in which a spring-loaded piston ( 6 ) can be moved axially with a piston rod ( 24 ), at least one spring-loaded spring ( 14, 16 ), a pressure line ( 20 ) for supplying pressurized fluid to the spring-loaded piston, wherein the emergency release device comprises an actuation device, an emergency release mechanism to interrupt the power flux between the spring-loaded piston ( 6 ) and the piston rod ( 18 ) and a holding device ( 30 ) for holding the emergency release device. The invention is characterized by a blocking device ( 48 ) to prevent engagement of the holding device ( 30 ) of the emergency release mechanism when the spring-loaded piston ( 6 ) is only partly released.

[0001] The invention relates to a pneumatically, hydraulically or electromechanically operated spring brake cylinder with an emergency release device having a housing, in which a spring-loaded piston is axially displaceable by means of a piston rod, having at least one spring-loaded spring, and, in the case of a design by means of a pneumatic or hydraulic operation, having a pressure connection for admitting pressure fluid to the spring-loaded piston, the emergency release device comprising an operating device and an emergency release mechanism for interrupting the flux of force between the spring-loaded piston and the piston rod with a holding device for holding the emergency release device which is designed for holding the emergency release device in different holding positions.

[0002] From German Patent Documents DE PS 26 08 502 and DE PS 27 48 540, brake cylinders are known with emergency release devices for the interruption and the automatic return of the braking function of a spring-loaded cylinder, in the case of which the emergency release lever for the emergency release must be operated or held until the accumulated spring force is completely reduced.

[0003] Although these solutions have been successful per se, when the operating or emergency release lever is not operated or held sufficiently long, at extremely low temperatures, conditions of the spring accumulator are conceivable which result only in a partial force reduction. Because of the viscosity of the lubricants, which increases with the falling temperature, the time period until the force is completely reduced is lengthened in comparison to higher temperatures. During this time period, the emergency release lever would therefore have to remain pressed in order to completely reduce the accumulated spring force.

[0004] Here, the invention uses a different approach. The invention starts with the recognition of the present problems and, in view of these problems, has the object of further developing the spring brake cylinder of the above-mentioned type such that situations are reliably avoided in which only a partial reduction or build-up of force takes place.

[0005] The invention-solves this task by means of the object of claim 1. The holding device for holding the emergency release device at different holding positions is in this case supplemented by a blocking device for preventing the holding of the holding device when the spring-loaded piston is only partially released, which prevents a holding, particularly an engaging of the emergency release operation when the spring accumulator is only partially released. Thus, for the emergency release of the spring accumulator, a one-time brief operation of the emergency release lever will be sufficient because the premature engaging of the blocking mechanism is reliably prevented by the blocking device.

[0006] According to a particularly preferred variant of the invention, the blocking device comprises a locking bar which locks the emergency release mechanism of the spring accumulator in the released position until the latter is completely released or is operative again.

[0007] In a cost-effective constructively simple further development, the holding device has a detent pawl acting upon a gear wheel. However, it is also conceivable that the holding device is designed to be rotating and/or linear and/or locking and/or clamping and permits several holding positions. A spring in the flux of force of the operation of the emergency release device in a simple manner prevents intermediate conditions of the detent pawl.

[0008] According to various embodiments of the invention, particularly the following locking bar arrangements are useful:

[0009] Between the spring-loaded housing and the spring-loaded piston, or

[0010] between the piston rod and the spring-loaded piston, or

[0011] between the piston rod and the spring-loaded housing.

[0012] Additional advantageous further developments of the invention are contained in the additional subclaims.

[0013] In the following, essentially two different basic embodiments of the invention and the blocking devices implemented within the scope of the invention will be described in detail with reference to the drawing.

[0014] FIGS. 1 to 6 are various views and operating condition of a first basic embodiment of the invention;

[0015]FIGS. 7a, b are views of a second embodiment of the first embodiment of the invention;

[0016] FIGS. 8 to 10 are various views of elements of a second basic embodiment of the invention;

[0017]FIG. 11 is a sectional view of a third embodiment of the invention.

[0018] First, by means of an example of embodiment 1 with reference to FIGS. 1 and 2, the function of the spring accumulator of the first embodiment of the invention will be described.

[0019]FIGS. 1 and 2 show two different views of a spring-loaded cylinder 2 having a housing 4 in which a spring-loaded piston 6: is arranged in an axially displaceable manner, on whose outer circumference sealing devices and sliding bands 8 a-8 c are distributed. The spring-loaded springs 14, 16 are arranged between the spring-loaded piston 6 and an axial housing cover 10 which is fastened on the inner circumference of the housing 4 by means of a snap ring 12.

[0020] Between the spring-loaded piston 6 and the housing 4, a pressure space 18 is constructed which can be acted upon by pressure by way of an air connection 20 in the circumference of the housing 4. The spring brake can be released and applied by the venting and bleeding by way of the air connection 20. When the spring accumulator 4 is not in the emergency-released operating condition, the force of the spring-loaded spring 14, 16 is supported by way of the spring-loaded piston 6 either on the pressure space or volume 18 or by way of a piston rod 24 on the spring loaded piston 6 on the braking device which is otherwise not shown here.

[0021] For releasing the engaged spring brake also without compressed air, the spring-loaded cylinder 6 has an emergency release device 26 which permits an interruption of the flux of force between the spring-loaded piston 6 and the piston rod 24.

[0022] In the illustrated example, the emergency release device 26 or the emergency release mechanism 26 is essentially based on the function of a spindle arrangement 28 with a detent pawl 30 which is swivellably disposed between two mutually axially offset sections 10 a and 10 b of the housing cover 10. The threaded spindle 32 of the spindle arrangement is constructed in the flux of force between the spring-loaded piston 6 and the piston rod 24. The resulting torque of the spindle arrangement is transmitted in the blocked condition by way of a displaceable guide 34 having an adjusting spring 36 to a gearwheel 38, which can be blocked or released by the detent pawl 30 (see particularly also FIGS. 2 and 5). For this purpose, one end of the detent pawl 30 engages in the gear wheel 38 in one of the operating positions of the emergency release device. In contrast, the other end-of the detent pawl 30 can be lifted out of the toothing of the gear wheel 38 by means of an emergency operating unit with a Bowden cable 42 and a restoring spring 44 constructed at the Bowden cable and a pressure spring 46, so that the rotation of the gear wheel 38 is released in this position of the detent pawl 30. As a result, the flux of force between the spring-loaded piston 6 and the piston rod 24 can be interrupted. The detent pawl 30 can be swivelled about an axis 31. A catch spring 33 presses its one end in the direction of the toothing of the gear wheel 38.

[0023] When the emergency release device is operated when a braking or spring force is applied to the piston rod 24, a rotation of the threaded spindle 32 will be caused so that the braking force is reduced and the spring-loaded piston impacts on the housing 4. In order to prevent another locking of the detent pawl 30 during the release operation, a locking bar 48 is arranged on the interior surface of section 10 b of the spring accumulator cover or housing cover 10, which locking bar 48 holds back the lifted-out detent pawl 30.

[0024] The locking bar 48 essentially has a bolt-type shape and, on its end facing the housing cover section 10 b, is equipped with a locking head 51. Between the two-part housing cover 10 a, 10 b (which has an indentation in this area) and the locking head 51 (with an axial recess), a locking spring 49 is arranged which presses the locking bar 48 in the direction of the detent pawl 30 and provides that, in one of the operating positions, the locking head 51 engages in a lateral stepped recess 35 of the detent pawl 30 for receiving the locking bolt 48 and locks the detent pawl 30 in its release position (see FIG. 5b). The section of the locking bar 48 facing away from the locking head has a bolt-type construction, the bolt-type section penetrating the interior housing cover section 10 a and, when the spring-loaded piston 6 is displaced, being displaceable by the latter in the direction of the housing cover 10, which compresses the locking bar spring 49 and presses the locking bar 48 out of its engaged position in the dent pawl 30 (FIG. 1). Only when the spring-loaded piston 6 after a release operation is again in the operative position, will the locking bar 48 release the detent pawl again for an engagement.

[0025] The optional display device 54 illustrated in FIG. 2 shows the “emergency-released” condition of the spring-loaded cylinder 2, in which the display device 54 is contacted by the. detent pawl 30.

[0026] Essentially; the following different positions of the spring accumulator are obtained before and after an emergency release operation: (Sequence: Operative—emergency releasing—operative)

[0027] 1. Spring-Loaded Cylinder 2 Released by Pressure (FIG. 3):

[0028] The spring-loaded cylinder 2 is released by the pressure in the pressure volume 18; the spring-loaded piston is displaced in the direction of the housing cover 10. No braking force is applied to the piston rod 24; the detent pawl 30 and the gear wheel 38 are in the locked condition.

[0029] 2. Spring-Accumulator in the Braking Position, Start of the Emergence Release Operation (FIG. 4):

[0030] The spring-loaded cylinder 2 is in its braking position; the pressure volume or the pressure space 18 is without pressure; the force of the spring-loaded springs 14, 16 is applied to the piston rod 24.

[0031] The emergency release operation is initiated by a pulling on the emergency release operation device. By way of the pressure spring 46 and the driving device 40, the detent pawl 30 is lifted out of the toothing of the gear wheel 38.

[0032]3. Emergency Release Operation, Detent Pawl 30 Locked (FIG. 5):

[0033] The spring-loaded springs 14, 16 are supported by way of the spring-loaded piston 6 on the spring-loaded housing cover 10. The piston rod is free of force; it was moved into its starting position by the back pressure spring 50.

[0034] By means of the engaged locking bar 48, the detent pawl 30 is held in its release position; the display device is active.

[0035] 4. Spring Accumulator Emergency-Released, Emergency Release Operation Withdrawn (FIG. 6):

[0036] The spring-loaded cylinder is in the “emergency-released” condition; the detent pawl 30 is locked; the emergency release operation device was moved into the starting position by the restoring spring.

[0037] 5. Spring Accumulator Which is Operative Again (FIG. 3)

[0038] The venting of the pressure volume 18 leads to the restoration of the readiness condition of the spring accumulator 2. The locking bar 30 holds the detent pawl in the released condition until the spring-loaded springs 14, 16 again have their prestress and the spring-loaded piston 6 takes up its right end position. After the engagement of the detent pawl 30, the tensional connection between the spring-loaded piston 6 and the piston rod 24 is restored.

[0039] In order to ensure the engaging of the locking bar in the detent pawl during an operation of the emergency release device, the pressure spring 46 is provided in the flux of force between the emergency release device and the driving device 40. The prestressing of the pressure spring 46 ensures the swivelling movement of the pawl 30 from the unlocking of the gear wheel 38 to the locking by means of the locking bar 48.

[0040]FIG. 7 shows a modification of the embodiment of FIGS. 1 to 6. In this embodiment, a free running device of the gear wheel, here, a cone clutch 52, is constructed in the flux of force between the spring-loaded piston 6 and the piston rod 24. The cone clutch 52 permits a reduction of the shock occurring during the emergency release operation because it ensures an unhindered continued running of the gear wheel 38 and of the threaded spindle 32 after the emergency release operation.

[0041] In the first embodiment of FIGS. 1 to 6 and the modification of this embodiment according to FIG. 7, the detent pawl and its locking device are situated in the spring-loaded or housing cover 10 which is fixedly connected with the spring-loaded housing 4. The locking bar 48 is operated by the spring-loaded piston. The pawl 30 itself is arranged between two sections 10 a and 10 b of the housing cover 10 which can be assembled.

[0042] The embodiment of FIGS. 8, 9 and 10 basically differs from the embodiment of FIG. 1 as a result of the arrangement of the detent pawl 30 and of the locking bar 48. The detent pawl 30 and the pertaining locking bar 48 are arranged on the piston rod 24. The locking bar 48 is moved by the threaded spindle 58 which is rotatable relative to the spring-loaded piston 24.

[0043] The second embodiment of FIGS. 8, 9 and 10 therefore shows another possibility of the locking bar arrangement. In this embodiment, the detent pawl 30 is rotatably arranged on the piston rod 34 by way of a bolt (in this regard, see the bore 30′ in the pawl 30; see FIGS. 10a, 10 b) and is operated by means of the spring-loaded piston 6. In this embodiment, the spring-loaded piston 6 and the spring-loaded spring 14 are arranged such that the pressure space 18 is situated on the right-hand side of the spring-loaded piston 6 in the drawing. The spring-loaded piston 6 is disposed on the threaded spindle 58 which, at one of its ends, if fixedly screwed to the spring-loaded piston 6 and, in its area facing away from the piston 6, is provided with a type of trapezoidal thread. In the area of the trapezoidal thread, the threaded spindle 58 is screwed into a sleeve 62 provided with a corresponding internal thread, which sleeve 62 is provided with an external toothing at its end facing away from the spring-loaded piston 6, so that the gear wheel 38′ is constructed in this area of the sleeve 62. In one of its operating positions, the detent pawl 30, which is arranged on an end area of the axially and radially displaceable holding plate 56, engages in the gear wheel 38′ and blocks it. An operation of the emergency release device displaces the plate 56 radially and releases the pawl 30 and thereby interrupts the flux of force between the spring-loaded piston 6 and the piston rod 24. In this case, the locking bar 48—pushed forward by the locking bar spring 49′—engages in an opening of the holding plate 56 and locks it radially. The locking bar 48 is released by the spindle 58 fixedly connected with the spring-loaded piston 6.

[0044] In this embodiment of the invention, the locking bar 48 is therefore arranged between the piston rod 24 and the spring-loaded piston 6. The locking bar spring 49′ is disposed between the piston rod 24 and the spring-loaded piston 6. The holding plate 56 is radially displaceable in an interior cylindrical attachment 63 of the brake cylinder housing and moves axially with the piston rod 24 and the spring-loaded piston 6. The radial displacement of the plate 56 takes-place by way of a coil spring 64 which is supported on a bolt 65 in the holding plate 56 and on a holding part 66 which, in an immobile manner, is screwed to the piston rod 24 and a bolt 68.

[0045] As an alternative, a locking bar operation is conceivable between the piston rod 24 and the spring-loaded housing 4. Such an embodiment is illustrated in FIG. 11. The basic construction of this embodiment is similar to the embodiment of FIGS. 8 to 10 with respect to the coupling of the spring-loaded piston 6. However, the locking bar 48 is., constructed such that it impacts during the moving of the piston rod from the spring-loaded housing 4 and, during a continued movement, is rotated about an axis 66. This rotating movement and a reverse rotating movement by the spring 49 between the piston rod 6 and the locking bar 48 move the locking bar 48 into its two operating positions and, in this manner, move it into and out of the recess 64 of the holding plate 56.

[0046] List of Reference Numbers

[0047] Spring-loaded cylinder 2

[0048] housing 4

[0049] spring-loaded piston 6

[0050] sealing devices/sliding bands 8 a-8 c

[0051] housing cover 10

[0052] snap ring 12

[0053] spring-loaded springs 14, 16

[0054] pressure space 18

[0055] air connection 20

[0056] piston rod 24

[0057] emergency release device 26

[0058] spindle arrangement 28

[0059] detent pawl 30

[0060] pawl spring 33

[0061] axis 31

[0062] threaded spindle 32

[0063] guide 34

[0064] recess 35

[0065] adjusting spring 36

[0066] gear wheel 38

[0067] driving device 40

[0068] Bowden cable 42

[0069] restoring spring 44

[0070] pressure spring 46

[0071] locking bar 48

[0072] locking bar spring 49

[0073] back pressure spring 50

[0074] locking bar head 51

[0075] cone clutch 52

[0076] display device 54

[0077] plate 56

[0078] threaded spindle 58

[0079] thread 60

[0080] sleeve 62

[0081] attachment 63

[0082] spring 64

[0083] bolt 65

[0084] holding part 66

[0085] bolt 68 

1. Pneumatically, hydraulically or electromechanically operated spring brake cylinder with an emergency release device having a housing (4), in which a spring-loaded piston (6) is axially displaceable by means of a piston rod (24), at least one spring-loaded spring (14, 16), and, in the case of a design by means of a pneumatic or hydraulic operation, having a pressure connection (20) for admitting pressure fluid to the spring-loaded piston, the emergency release device comprising an operating device and an emergency release mechanism for interrupting the flux of force between the spring-loaded piston (6) and the piston rod (24) with a holding device (30) for holding the emergency release device which is designed for holding the emergency release device in different holding positions, characterized in that a blocking device (48) is provided for preventing the holding of the holding device (30) of the emergency release mechanism while the spring-loaded piston (6) is only partially released.
 2. Spring brake cylinder according to claim 1, characterized in that the blocking device has a locking bar (48) which locks the holding device (48) in its released position until the spring-loaded piston (6) is completely released.
 3. Spring brake cylinder according to one of the preceding claims, characterized in that the holding device (30) has a detent pawl (30) acting upon a gear wheel (48).
 4. Spring brake cylinder according to one of the preceding claims, characterized in that the holding device (30) is designed to be rotating and/or linear and/or clamping and permits several holding positions.
 5. Spring brake cylinder according to one of the preceding claims, characterized by at least one spring (44, 46) in the flux of force of the emergency release device for avoiding intermediate conditions of the detent pawl (30).
 6. Spring brake cylinder according to one of the preceding claims, characterized in that the locking bar (48) is arranged between the spring-loaded housing (4) and the spring-loaded piston (6), or between the piston rod (24) and the spring-loaded piston (6), or between the piston rod (24) and the spring-loaded housing (4).
 7. Spring brake cylinder according to one of the preceding claims, characterized in that the force of the spring-loaded spring (14, 16) is supported by way of the spring-loaded piston (6) either on the pressure space (18) or by way of a piston rod (24) on the spring-loaded piston (6).
 8. Spring brake cylinder according to one of the preceding claims, characterized in that, in the flux of force between the spring-loaded piston (6) and the piston rod (24), as an element of the emergency release mechanism, a threaded spindle (32) is arranged.
 9. Spring brake cylinder according to one of the preceding claims, characterized in that the torque of the threaded spindle (32) is transmitted by way of a displaceable guide (34) with an adjusting spring (36) to the gear wheel (38) which can be locked by the detent pawl (30).
 10. Spring brake cylinder according to one of the preceding claims, characterized in that the emergency release operating unit has a driving device (40) for driving the detent pawl (10), a Bowden cable (42) and at least one restoring spring (44) and a pressure spring (46) on the Bowden cable (42).
 11. Spring brake cylinder according to one of the preceding claims, characterized the locking bar (48) essentially has a bolt-type shape and, at its end facing the housing cover section (10 b), is equipped with a locking bar head (51) which is designed for engaging in a recess (35) of detent pawl (39).
 12. Spring brake cylinder according to one of the preceding claims, characterized in that a locking bar spring (49) is arranged between the housing cover (10 a, 10 b) and the locking bar (48), which locking bar spring (49) presses the locking bar (48) in the direction of the detent pawl (30).
 13. Spring brake cylinder according to one of the preceding claims, characterized in that the locking bar (48) can be displaced by the spring-loaded piston (6) from its locking position in the detent pawl (30).
 14. Spring brake cylinder according to one of the preceding claims, characterized in that, in the flux of force between the spring-loaded piston (6) and the piston rod (24), a free running device (52) is provided for the gear wheel (38).
 15. Spring brake cylinder according to one of the preceding claims, characterized in that the free running device is constructed as a cone clutch (52).
 16. Spring brake cylinder according to one of the preceding claims, characterized in that the detent pawl (30) and the locking bar (48) are arranged on the piston rod (24).
 17. Spring brake cylinder according to one of the preceding claims, characterized in that the locking bar (48) can be operated by the threaded spindle (32) connected with the spring-loaded piston (24).
 18. Spring brake cylinder according to one of the preceding claims, characterized by a display device (54) for displaying the operating condition of the emergency release device.
 19. Spring brake cylinder according to one of the preceding claims, characterized in that the detent pawl (32) is arranged on a holding plate (56) which is radially displaceable in a cylindrical attachment (63) of the cylinder housing (4) such that, as a result of a radial displacing of the holding (56) and of the detent pawl (30), the gear wheel (30′) releases or blocks.
 20. Spring brake cylinder according to one of the preceding claims, characterized in that the locking bar (48) is arranged on the piston rod (24) and is designed for, in an operating position, engaging in a recess of the holding plate (56) and radially locking the latter.
 21. Spring brake cylinder according to one of the preceding claims, characterized in that the locking bar (48) is swivellably disposed on the piston rod (24) such that, during axial movements of the piston rod, it can be swivelled from the cylinder housing (4) into and out of a recess of the holding plate (56). 